Processing facilities and other facilities routinely include tanks for storing liquid materials and other materials. For example, storage tanks are routinely used in tank farm facilities and other storage facilities to store oil or other materials. As another example, oil tankers and other transport vessels routinely include numerous tanks storing oil or other materials.
Online automatic monitoring of storage tank facilities is an important application for tank farms and other facilities. For example, sediment or sludge can collect at the bottom of a storage tank. This sediment or sludge typically cannot be automatically pumped out of a storage tank. The sediment or sludge can continue to grow above the bottom of the tank over time. If the height of the sediment or sludge becomes too high, mega-watt mixers often have to be used in order to remove the sediment or sludge, which consumes lots of energy.
Current methods for inspecting the sediment or sludge in a storage tank are time consuming, hazardous, and very expensive. For example, in some approaches, operators actually go to tank roofs and perform hand dipping of instruments at a limited number of points. However, large storage tanks often have diameters of tens of meters, and the limited discrete points of inspection are typically not adequate to cover the complete area of the tank bottom. Other inspection methods require shutdown of a tank's operation and emptying of any stored material from the tank. That inspection can therefore result in lost revenue because no tank operations are occurring. Also, even though robots are often used in chemical cleaning processes in some advanced facilities, most refineries and other facilities do not know when a cleaning process is needed. Rather, these facilities simply follow certain periodic manual inspection schedules. This is true in finished goods storage tanks and other tanks, as well.